1. Field of the Invention
The present invention relates to a vehicle diagnosing apparatus for communicating with an electronic control unit mounted on a vehicle from outside the vehicle and determining whether or not the vehicle has passed with respect to a plurality of diagnostic items based on various data transmitted from the electronic control unit.
2. Description of the Related Art
When vehicles with electronic control units (ECUs) installed therein are manufactured, they are diagnosed to check if the ECUs and various devices electrically connected thereto function properly or not in a final inspection process after the vehicles have been assembled. Such a diagnostic process is carried out on a vehicle by communicating with a vehicle diagnostic apparatus (tester) that is positioned outside the vehicle and connected to the ECU in the vehicle (see, for example, Japanese Laid-Open Patent Publication No. 2000-121684 (hereinafter referred to as JP 2000-121684 A) and Japanese Laid-Open Patent Publication No. 09-210865 (hereinafter referred to as JP 09-210865 A)).
According to JP 2000-121684 A, in order for a disclosed inspection system to shorten its inspection time, data detected by an ECU (10) are temporarily stored in a RAM (23) and then output all together to an inspection tester (100) (see the abstract of JP 2000-121684 A). More specifically, according to JP 2000-121684 A, the inspection system enters an inspection mode in response to a communication request sent from the inspection tester to the ECU (see paragraph [0017]), and the ECU stores various data in the RAM (see paragraphs [0028], [0030] through [0032]). In response to the communication request from the inspection tester, the data stored in the RAM are sent from the ECU to the inspection tester (see paragraphs [0039], [0043]).
According to JP 2000-121684 A, as described above, the ECU sends the data for inspection to the inspection tester in response to the communication request from the inspection tester. However, the communication request from the inspection tester is effective only to put the inspection system into an inspection mode (see paragraph [0017]), but is not capable of requesting the ECU to send any particular detected data.
Consequently, the inspection system disclosed in JP 2000-121684 A is not applicable where the inspection tester is to execute a plurality of diagnostic programs concurrently with each other and each of the diagnostic programs is to acquire the detected data from the ECU.
The inspection system disclosed in JP 2000-121684 A is designed to send the detected data stored in the RAM from the ECU to the inspection tester, i.e., to reduce communication loads at the time the detected data are sent from the ECU to the inspection tester. However, the disclosed inspection system does not take into account any attempts to reduce communication loads at the time data are sent from the inspection tester to the ECU.